Do you have the expertise to evaluate his expertise? Did the person who granted you proof of this expertise also have sufficient expertise to do so? What about

Do you have the expertise to evaluate his expertise? Did the person who granted you proof of this expertise also have sufficient expertise to do so? What about the person above that? What is the root of expertise? Plato with his allegory of the cave, casually dismissing claims that come from the wrong mouths in his lofty opinion? In my mind it would be simpler to evaluate claims as they are rather than bringing the speakers life story into it.